Re: kern/55663 (Support for EVFILT_USER in kqueue(2))

[Ruslan Nikolaev <nruslan_devel%yahoo.com@localhost>]

The following reply was made to PR kern/55663; it has been noted by GNATS.

From: Ruslan Nikolaev <nruslan_devel%yahoo.com@localhost>
To: gnats-bugs%netbsd.org@localhost, jnemeth%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/55663 (Support for EVFILT_USER in kqueue(2))
Date: Tue, 20 Oct 2020 23:33:49 -0400

 Also just to add regarding pipe-based solutions, some applications 
 decided to use EVFILT_USER instead. Looking on the Internet show the 
 following results (since 2010): e.g. libevent:
 
 Date: Fri, 17 Sep 2010 00:34:13 -0400
 Subject: Replace pipe-based notification with EVFILT_USER where possible
 Commit: 53a07fe2f95c360d060b9fd58dfcd929c2c1aac2
 
 Sufficiently recent kqueue implementations have an EVFILT_USER filter
 that we can use to wake up an event base from another thread.  When
 it's supported, we now use this mechanism rather than our old
 (pipe-based) mechanism.  This should save some time and complications
 on newer OSX and freebsds.
 ---
 
 https://sourceforge.net/p/levent/mailman/levent-commits/?viewmonth=201204